The image scanner has been known which comprises photoelectric converters for translating optical information into electric signals, and analog switches for electrically scanning the photoelectric converters to selectively obtain the electric signals. The analog switches may take the form of field-effect transistors (FETs) disposed adjacent the photoelectric converters, as taught by Japanese Unexamined Patent No. 63-2377 laid open to public inspection on Jan. 7, 1988.
In an image sensor fabricated in the form of an integrated circuit, each FET must be sized to fit the width (e.g. 125 micrometers) of one photoelectric converter, that is, of one picture element. However, it is no easy task to form the FETs of that size. The difficulty increases as the three wiring conductors of minimum widths for the drain, source and gate of each FET must be formed on prescribed narrow parts of the baseplate.
The present invention aims at the provision of a scanning circuit utilizing diodes which have a smaller number of electrodes than transistors.